* {
  margin: 0;
  padding: 0;
}

.father {
  position: relative;
  width: 400px;
  height: 400px;
  margin: 300px;
  background-color: pink;
  overflow: hidden;
}

.son {
  position: absolute;
  top: 10px;
  left: 20px;
  width: 150px;
  height: 150px;
  background-color: purple;
}